My second white plastic expansion tank has developed a leak and needs to be replaced. Is there a better unit available that won't break down under the heat of the engine? We have a 2000 DSDP FRT with a 3126b Cat. I need to get it replaced before we head south for the winter in about 3 weeks. Thanks for any assistance that you provide.

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My second white plastic expansion tank has developed a leak and needs to be replaced. Is there a better unit available that won't break down under the heat of the engine? We have a 2000 DSDP FRT with a 3126b Cat. I need to get it replaced before we head south for the winter in about 3 weeks. Thanks for any assistance that you provide.

I have a 2001.5 Discovery with a 3126E Cat! After hearing of expansion tank failures I closely examined mine and found it to be sound with no signs of stress cracks. Out of curiosity, I checked with a local Freightliner Dealer and they quoted $87.00 for a new tank. According to the parts person, the OE tank has no replacement! It may be possible to have a local sheetmetal shop fab a replacement tank from aluminum.

We had one of these tanks explode in Nebraska several years ago. I found that the fan control module had gone bad and was causing the cat to run hot. After replacing the module and the tank we've had no more problems. Plus the temps stay down on long hill climbs.

I would be very careful trying to fabricate an aluminum tank to replace the plastic tank might cause more problems than it solves.

After visiting the local Freightliner store I found out that the tank has been redesigned with a different material. I have ordered a new one and it should be here in about 10 days. Newer engines using this style use larger hoses and the tank is built to accomodate the larger hoses. An adapter kit is available to mate to the smaller hoses on the older engines. The tank price is about $130 now. We have to pay for the new technology!! I should have noted previously that this is the second tank failure for this 11 year old coach.

Just replaced my tank with a model made for semi's. The Freightliner RV tank was quoted at $600 plus labor (it's metal). A few old exact replacement tanks can be found, but they were quoted at almost $300 plus labor. My replacement tank from Freightliner was $110 and I put it in myself. Some of the metal brackets had to be cut and bent, but that only cost me $35 plus a short piece of hose and some clamps. It was really very simple. There was a nice posting on this forum on how to do the installation and even came with some nice photos. If you want to do the project yourself, email me at bbohnnd@midco.net and I should be able to forward the pics to you. Good luck.

Ya know, we just left Albuquerque, NM and are here near Sedona, AZ a distance of about 400 mi. When we arrived I notice a rather large drop in the level of that polypropelene boiler coolant inside this white translucent expanson tank located right inside the engine access door on our motor home (Essex 4502, 2008).

Well, previously I had to use pipe strap to re-attach the right hand flange on this tank used to attach the tank to the cross member frame. Left hand flange seemed o.k.

After reading the above discussion, I'm thinking we too might have developed a leak and will check closer.

Since I was unable to locate the pink boiler coolant locally, I called Carl at Newmar who directed me to www.RhomarWater.com/distributors/ in order to find a local distributor. The closest source to our Sedona location is....SALT LAKE CITY !!! Well, guess I'll have to call em on Monday to see if they can ship me a gallon. Boy, obtaining this coolant ain't an easy thing.

Too bad there isn't a more durable expansion/reservoir tank for this purpose. Seems like the white translucent plastic tanks just are holding up well.

I would look for a local Cat or Cummins shop (your engine). They should have the correct coolant for your engine. At least there will be something in Phoenix, which is a bunch closer than SLC.
The new tank is supposed to be made from a different material. Hopefully this is better.

Now, this translucent/plastic "expansion tank" you're talking about contains this clear pink polypropylene glycol special coolant fluid which is specially formulated so as NOT to damage aluminum surfaces in the cooling system. Right??

Also, this coolant should NOT be replaced with polypropylene anti-freeze/coolant found everywhere since this common anti-freeze/coolant might damage such aluminum surfaces. Right?

Now for my REAL DUMB question. (Anyone???):

Does this expansion tank only provide circulating "coolant" for the engine like the radiator water/antifreeze fluid in a car?...or....does this coolant reservoir also serve as the fluid source for the fluid circulating through the rigs furnace/heater (ie., Hydro/Aqua Hot or Oasis type) to the heat exchangers throughout the cabin compartments as well as for the engine coolant????

Somewhere I had the idea that the translucent reservoir served as the coolant source for BOTH the cooling of the engine, AND, the furnace heat exchanger system.

With your Essex the clear tank in the engine compartment is for the Oasis hydronic heating system. The Oasis povides unlimited hot water and 3 zones of heat zone 1 3 anf 4.
To heat the coach it heats and circulates the pink liquid in the overflow tank then circulates the coolant to a radiator at each zone. Air passed through the radiator and is heated. It takes a special kind of coolant, one that is designed for hydronic heating. Do not use the red rv anit-freeze found at walmart. I have a Aquahot (same type systm different manufacture) and I useCamco -100 degree Boiler Fluid Concentrate - Detailed item view - Parts - RV Hydronic Heater Repair.
This system has nothing to do with your engine coolant system the overflow tank for it is to the right of the engine compartment and is metal with a automotive type radiator cap and a sight glass to check the collant level.

Thanks SO MUCH for your help. I'm no whiz when it comes to this stuff and the OP's question and the responses had me confused regarding what they referred to as the "white, plastic, coolant expansion tank." I thought I understood correctly (as your reply confirmed) that the white translucent tank in our rear engine compartment was indeed solely for the furnace heating, and, that the Final Charge engine coolant tank (metal w. radiator type cap) is the separte tank, and, that the hydraulic fluid tank (metal/cylindrical w. little dip stick) is the 3rd tank.

Anyway.......THANKS AGAIN FOR YOUR KIND TOLERANCE AND HELP!!

P.S. Do you know, is that "Camco" boiler coolant equivalent to the RhoGard coolant (by Rhomar, Inc.) that Carl at Newmar directed me to?? If so, I wonder if the Camco is easier to find?

You are correct on the 3 tanks. I had trouble finding the cacmo boiler cololant also. Funny thing I was in a rv dealer in Panama City, FL and they carry it. If Carl recommends the coolant I am sure you can use it.